Method of welding



Patented Feb. 18, 1936 l UNiTaDsTATEs PATENT oFFicE 6 Claims. (Cl. 113-35) 'I'his invention relates to the production of pipe and care must be exerted to have the weld conand like tubular metal articles by welding, and l tinuous and unbroken throughouthas to do more particularly with the method or' I have found that there are certain advanwelding. gages, of considerable value from'the practical 5` The method of my invention is especially suited standpoint. in Winding the metal strip s0 85 t0 5 for use in the production of tubular structures, Provide a lap J'Oini vbetween the adjseent convosuch as pipes and the like, from metal strip by lutions and welding the overlap of this joint to winding the strip spirally and welding together the Undel'lelp along n line spaced inward flOnl theconvolutions of the wound strip, though, in the leading edge, f the Overlap- In B Pipe 91'0- 10 its broader aspects, it can be used to advantage duced in this ma'nel' the Portions 0f the Vel'laD 10 `for other purposes. It is known to wind meta1 at the sides of the line of the weld constitute, in strip spirally and edge-weld together the coneiect, collars which extend around the undervoiutions of the wound strip to form pipe and lap and are shrunk tightly thereabout as the like tubular articles. In forming pipe in this mete-100015 after the Welding Operatien- These l5 manner care must be exerted to assure that the Collars 101111 duid-tight Closures about the 11nl5 weld is continuous and unbroken throughout, derlap at Opposite sides 0f the Weld. the inner particularly ifthe pipe ist() be used for conductone of which is eiective to prevent leakage in ing fluid under appreciable pressureq Any breaksl the event the weld is defective or brokenv at any or weakness in the weld renders the pipe unfit point' these 'collars 315.0 Serving as enforcing S0 for the use intended. This necessity i'or care elements for the pipe and the joints thereof- In 20 makes imperative the employment of operatives .Producing a' pipe in this I nanner particularly if of exceptional and the welding operation is heavy or mick metal stm is used appreciable necessarlly performed at W Speed, au of which i time is required for the heat to penetrate the full adds materially to the cost of production lthickness of the overlap and to heat the under- Pipe used in handling uids under high pres lap to proper welding temperature. This meth- 25 I sures must be made of thick metal to withstand 0d is. therefore open to the objection that the the severe stresses to which it is subjected. This weldmg Operation has to be performed at .low pipe may be produced by spirauy winding metal speed if the thickness of the overlap along the strip and edge we1dmg *together the convolutions line of weld is the same as that oi the remainder of the wound strip, as above. Itis also known to gg aMneilvgbglegelllmg 30 prduce such pipe by Winding thick metal strip eration may be performed at high speed in the splrauy with the leadmg edge portion of each production of a pipe or tubular article formed convolution overlappingthe following edge porfrom metal Strip wound spirally to DIOVde lap tion of the next preceqmg convolutlon so as to joints between the adjacent convolutions of the form a lap joint therewith, and to edge-weld the Wound Strip While assuring a. continuous and overlap of the joint to the underlap. The use of unbroken Weld Whll my lnventign l5 particuheavy or thick metal strip introduces dimculties larly suitable 'for use with material of heavy with respect to .the welding operation which have gauge, it can also be used to advantage with ma.-

40 proven to be quite serious in practice. When the terlal ,of lighterv gauge Further objects and ad- 40 convolutions of the wound strip are edge-welded vantages of my invention will appear from the together it is necessary, in order to assure a relidetained description. l d

able weld, that the heat penetrate the entire In the drawing; thickness of the adjacent edge portions of the Figure 1 is a fragmentary plan View' lllustmtconvolutions oi' the wound strip, while avoiding ing the method of my invention, of a pipe formed 45 burning of the metal. This inevitably slows down from metal strip spirally wound to provide lap the Weldlng Operation Where the Strip is Wound joints between adjacent convolutions of the wound so as to provide lap joints between adjacent constrip;

volutiOn-S. great care iS required t0 avoid Objec- Figure 2 is a section taken substantially on the tionable burning of the leading edge of the. overline 2-2 of Figure lon an enlarged scale; 50 lap or the burning of a. hole through the under. Figure 3 is a fragmentary section takenl sub` lap in heating. the edge of the overlap and the stantially on 'theline 3-3 of Figure 1 on aneuadjacent portion of the underlap to proper weldlarged scale; ing temperature. This also means that the weld- Figure 4 is a fragmentary sectional` view ing operation must be performed at low speed through a Vlap joint of the pipe illustrating the 5.5

-ing the completed weld.

Various machines are known in this artfor winding metal strip spirally and welding the wound convolutions of the strip together to form pipe and like articles, and it is not necessary to illustrate or describe in detail any particular machine-for performing this operation, in describing my invention. Sumce it to say that any suitable machine may be employed for winding the strip in the manner stated and advancing the pipe or like article as formed.

I have illustrated the method of my invention, by way of example, as used in the production of l' a pipe I or like tubular article from metal strip 2 which is wound spirally to form convolutions, the forward portion of each convolution overlying the rearward portion of the next preceding convolution and forming therewith a lap joint, the overlap being welded to the underlap by suitable means, 'comprising an-electrode 3 beneath which the wound strip travels in such manner that the overlap is welded to the underlap along a line spaced inward from the leading edge oi' the overlap.v

'I'he metal strip 2 may be specially formed preliminarytoitsbeingpassedthroughtheforming and winding machine ior producing the pipe or other tubular article. Conveniently, this metal strip is rst passed through a rolling machine which shapes it so as to provide, at one side of body 4 of the strip, an offset portion 5 of appreciable width having in one iacev a troughshaped groove 6 of considerable depth and. disposed inward from outer edge 1 of the offset portion 5, this groove extending lengthwise of the strip and parallel to edge 1. The other side of the strip is tapered at4 8 correspondingly to the curvature 9 at the inner side of the face of portion 5 opposite to groove 6. This groove 6 is of considerable depth, as noted, so that the metal between the bottom of the groove and the underface of strip 2, at I0, is much thinner than the metal of the strip at the sides of and adjacent the groove. While strip'2 is preferably formed in the manner described, in a rolling machine, any other suitable or preferred means may be employed for properly forming the strip, and the groove 6 may be of the particular shape illustrated or of any other suitable shape.

The strip 2, formed in the manner illustrated and described, is then passed through a suitable machine which serves to wind the strip spirally in such manner that the forward offset portion 5 oi' each convolution of the wound strip overlies the rearward portion of the next preceding convog lution so as to form a lap joint therewith. As the strip is wound and the formed pipe or article I is advanced, trough 6 passes beneath the electrode 3 and the welding operation proceeds. Since the welding occurs along a line corresponding to the trough 6, the relatively thin area I0 of the overlap is subjected to the heat of thev arc and the heat quickly penetrates through this relatively thin area of Ymetal so as to' fuse the same and heat the underlying portion of the underlap to welding temperature. This enables the welding operation to'be performed athigh speed. due to the provision of the thinned area of the metal strip 2 corresponding to the line of the weld, thus effecting a material saving in time, which is an important consideration. Furthermore, thinning of the metal at the area IB assures that the heat readily penetrates the underlap to the proper depth to assure a continuous and mechanically strong weld between the overlap and the underlap. This will be clear from Figure 4. Preferably, though not necessarily, the electrode 3 is disposed adjacent the top of the pipe being formed, and to lone side of thevertical plane of the axis thereofin the direction in which the formed pipe is rotated. as

shown in Figure 3. The molten metal of the overlap iiows toward previously molten and congealed metal of the overlap so as to be puddled thereby, thus assuring an/eifective union of the metal oi the overlap and the metal of the underlap, which contributes to a highly eiiicient weld. During the welding operation the sidewalls of the trough 6 are heated by the arc and tend to cave in to a certain extent, the molten metal thus produced, together with the molten metal from the bottom of the trough, flowing toward the previously molten and congealed metal -so as to be puddled thereby in the manner above described. As a result of the melting ot the metal at the sides of the trough, the trough is lled in to a certain extent so that the thickness of the metal along the line of the completed weld is appreciably greater thanpthe thinned area IU of strip 2 before the welding operation, as shown at Illa in Figure 5. If desired, the trough Ii may be completely lled during the welding operation,

' by Supplying additional metal to the trough in a suitable manner. In Figure 6 I have shown a metal rod I I so disposed as to be subjected to the heat of the arc, the additional molten metalv, thus produced owing into the trough so as to completely fill the latter, as indicated at IIIb in Figure '1. The weld thus produced is of the same thickness as the adjacent portions of the metal strip 2- and is at least equal in mechanical strength to these portions of the strip. This provides an exceptionally strong weld which, ii' desired, may be ground dofwnV or smoothed ofi flush with the outer face of the overlap of the joint.

In the embodiment of my invention illustrated, the electrode 3 is a carbon electrode such as is commonly used in vwelding operations. If desired, a metallic electrode may be employed and the metal of this electrode utilized for lling in the trough 6, instead oi' the metal rod I I.

Metal electrodes suitable for this purpose are known in the art and need not be illustrated nor described in detail, since the use of such an electrode in place of the carbon el readily understood by those skill in the art. f

lrodeawmbeA Since the area I0 of strip 2 is quite thin relative tothe adjaoentportion of the strip, the heat will readily penetrate thisi thin area thus Veliminating danger of burning oi' the overlap,

such as'is apt to occurwhere excessive heat is emplyed. As above stated, the trough ,6 may be`\of any suitable shape provided the required area of the strip is thinned to the desired extent.

My invention contemplates, in its broader aspects, thinning the area of the metal strip corresponding to the desired line of weld in any suitable manner and to the proper extent to permit of high speed welding, particularly when using relatively thick or heavy material. It will be understood, however, that the method of my invention is not limited to thick or heavy material, since it can be applied to advantage to iaterial of any gauge commonly used in` the roduction` of pipe and like tubular articles. 'ests have. shown that by thinning the metal trip along the line of the weld to be made, i the manner described, the welding operation an be performed entirely satisfactoril'yat least nree times as fast as is possible when-the'st-rip snot so thinned, for any given thickness of trip, depending more or less upon thev extent o which the strip is thinned.

In the formed pipe, tapered portion 8 of the trip fits snugly into the curve 9 o f portion 5 f the overlap so as to eliminate fobjectionabl rojections within the pipe. This is not essenial, how`ever, and the strip may be provided with he tapered portion 8 or not, as desired or onditions may require. Also, while'it is pre'- erred to oifset the forward portion of the strip, is at 5, this is not essential to the method of my nvention and the strip may be otherwise suitbly formed.

It is known in this art to form the pipe or ike article first by rolling the metal strip spirally' o form lap joints between the convolutions, the vound strip being secured together by suitably maced tack welds or in any other suitable man- 1er, and then secure the convolutions of the wound pipe together by welding performed as a ieparate operation from that of winding of the strip. I contemplate employing the method of ny invention for welding a pipe or like article either during the winding ofo the metal strip, or after the metal strip has been wound into pipe form as above.

The forming of the groove in the forward portion,of the metal strip preliminary to winding thereof into pipe form is not essential to my lnvention, though advantageous in certain cases. lf desired, the metal strip may first be wound lnto pipe form, with the convolutions of the wound strip temporarily held against unwinding, after which the groove I may be formed in the forward portion ofthe strip along the line of the desired weld, by suitable means known in the art. and the convolutions of the wound strip may then be welded together along the line of the groove.

My invention comprehends the thinning of the metal of the overlap along the desired line of weld disposed away from the leading edge of the overlap, either before, during, or after winding of the metal strip spirally to form the pipe or like article, and vwelding the overlap to the underlap along this thinned area either during the winding of vthe strip or after the metal strip has been wound to form the pipe.

What I claim is:-

1. The method of producing tubing from metal strip by welding, which comprises providing the metal strip with a trough-like lengthwise groove in one face and spaced from one edge thereof, thereby rendering the grooved portion of said strip of materially less thickness than the adjacent portions thereof, winding the strip spirally into tubular form with the forward grooved portion of each convolution overlying therearward portion of\the next preceding convolution and forming therewith a lap joint in which the groove is disposed correspondingly to the desired line of weld and the grooved face of the strip is disposed outermost, subjecting -the thinned portion of the overlap to heating means while imparting relative movement to said means and to the wound strip along said groove, thereby melting the thinned portion of the overlap along the groove and heating the underlying portion of the 'underlap to welding temperature, filling the groove by additional metal melted by 'the heating means, and flowing the molten metal of the overlap and the additional molten metal toward previously molten and congealed `metal of the overlap and additional metal so as to be puddled thereby, thereby securing the overlap tothe underlap by a line of'welding corresponding to the thinnedportion of said strip and of substantially the same thickness as the adjacent unthinned portions of the strip.

2. The method of producing tubing from metal strip by welding, which comprises providing the metal strip with a trough-like lengthwise groove in one face and spaced from one edge thereof, thereby rendering the grooved portion of said strip of materially less thickness than the adjacent portions thereof, winding the strip spirally into tubular form with the forward grooved portion of each convolution overlying the rearward portion of the next preceding convolutionk and forming therewith a lap joint in which the groove is disposed correspondingly to the desired line of weld and the grooved face of the strip is disposed outermost, subjecting the thinned portion of the overlap to heating means while imparting relative movement to said means and to the wound strip along said groove, thereby melting the thinned portion of the overlap along the groove and heating the underlying portion of the underlap to welding temperature, and filling the groove by additional metal melted by the heating means, thereby securing the overlap to the underlap b'y a line of welding corresponding to the thinned portion of said strip and of substantially the same thickness as the adjacent unthinned portions of the strip.

l 3. The method of producing tubing from metal strip by welding, which comprises providing the metal strip with a trough-like lengthwise groove in one face and spaced from one edge thereof, thereby rendering the grooved portion of said strip of materially less thickness than the adjacent portions thereof, Winding the strip spirally into tubular form with the forward grooved portion of each convolution overlying the rearward portion of the next preceding convolution and forming therewith a lap joint in which the groove is disposed correspondingly to the desired lin'e of weld and the grooved face of the strip is disposed outermost, subjecting the thinned portion of the overlap to heating means while vimparting relative movement to said means ,and to the wound strip along said groove, thereby melting the thinned portion of the `overlap along the groove and heating the underlying portion of the underlap to welding temperature, and flowing the molten metal of the overlap toward previously molten and congealed metal of said overlap so as to be puddled thereby, thereby securing the overlap to the underlap by a line of welding corresponding to the thinned portion of said strip.

4. The method of producing tubing from metal strip by welding, which comprises providing the metal strip with a trough-like lengthwise groove in one face and spaced from one edge thereof, thereby rendering the grooved portion of said strip of materially lessthickness than the adjacent portions thereof, winding the strip spirally into tubular form with the forward grooved por'- tion of each convolution overlying the rearward portion of the Anext preceding convolution and forming therewith a lap joint in which the groove isdispedconespondingiytouieodesirednneofl weld and the grooved face of thestrip is disposed outermost, and subjecting the thinned portion of the overlap to heating means while imparting relative movement tovsaid means and the wound strip along said groove, thereby melting the thinned portion of the overlap along the groove and heating the underlying portion of the underlap to welding temperature and forming a. line of welding securing said overlap and said underlap together and corresponding to the' thinned portion of said. strip.

5. The method of producing tubing from metalv ward portion of the next preceding'v convolutio: and forming therewith a lap joint, and weldin the overlap of the joint to the underlap alon said groove. f

6. 'Ihe method of producing tubing from meta strip by welding, which comprises providing th metal strip with a thinned area extending length wise of the strip and disposed inward from on edge thereof, said area being materially thinne than the adjacent unthinned portion of thefstri; winding said strip spirally into tubular form wit] the forward thinned portion of each convolutioi overlying the rearward portion of the nekt pre ceding convolution and forming therewith a la] Joint, and welding the overlap of the joint to thl underlap along said thinned area of the overla] with the line of welding spaced inward of th overlap away from the leading edge of the latter EDWARD HALL TAYLOR. 

